New And Significant Accounting Policies (Components Of Net Periodic Benefit Cost) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 99		$ 82
Interest cost	164		164
Expected return on plan assets	(149)		(167)
Amortization of prior service cost	5		9
Amortization of unrecognized loss	31		12
Net periodic benefit cost	150		100
Less: transfer to regulatory account	(75)	[1]	(36)	[1]
Total	75		64
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	12		11
Interest cost	21		23
Expected return on plan assets	(19)		(20)
Amortization of transition obligation	6		6
Amortization of prior service cost	6		6
Amortization of unrecognized loss	1		1
Net periodic benefit cost	27		27
Total	$ 27		$ 27

[1] The Utility recorded $75 million and $36 million for the three months ended March 31, 2012 and 2011, respectively, to a regulatory account as the amounts are probable of recovery from customers in future rates.